Method of crimping yarn

ABSTRACT

YARN IS C RIMPED BY FORMING IT INTO A CHAIN OF STICHES, SETTING THE CHAIN OF STITCHES IN THE CONFIGURATION OF THE   STITCHES WHILE THE CHAIN IS UNDER TENSION, AND THEN UNRAVELLING THE YARN FROM THE CHAIN. APPARATUS FOR CRIMPING INCLUDES A DEVICE FOR KNITTING YARN INTO A CHAIN OF STITCHES, POSITIVE DRIVING MEANS FOR CONVEYING THE CHAIN UNDER TENSION PAST A HEATER, AND MEANS FOR UNRAVELLING YARN FROM THE CHAIN OF STITCHES.

Mamh 1971 D. A. E. MATTINGLY I 3,568,277

' 7 METHOD OF CRIMPING YARN Original Filed July 8. 19.66 '7 Sheets-Sheet 1 J4 Hy 2/ v v vmrls A 15:?? EDWAKP WW D. A. E. MATTINGLY March9, 1971 METHOD OF CRIMPING YARN Original Filed July 8. 1966 7 Sheets-Sheet l Maid: 9, 1911 5. M1. MAT'mGLY 3,56 7

METHOD OF CRIMP ING YARN 7 Original Filed July 8. 1966 7 Sheets-Sheet 5 WI/[Nrok om A/bCYMQ/W 5 Ry ,IQWQ/L ATT March 1 f D. A. E. MATT INGLY 3,558,277

v METHOD OF CRIMPING YARN Original Filed July 8, 1966 7 Sheets-Sheet 4 By M 9 AIWW/VEXS D. A. E. MATTINGLY 3,568,277

METHOD OF CRIMPING YARN March 9, 1971 7 Sheets-Sheet 6 1 ori inal" Filed July 8, 1966 D. A. E. MATTINGLY METHOD OF CRIMPING YARN Original Filed July 8, 1966 March 9,1971

7 Sheets-Sheet '7 INVENTOR:

b51118 ALSERT EDHARJ) MATT/NAIL) ATTORNEYS US. Cl. 28'72.16

United States Patent 3,568,277 METHOD OF 'CRIMPING YARN Denis Albert Edward Mattingly, London, England, as-

signor to The Klinger Manufacturing Company Limited, London, England Continuation of application Ser. No. 830,202, May 26, 1969, which is a continuation of application ser. No. 563,874, July 8, 1966. This application Jan. 29, 1970, Ser. N 0. 7,396 Claims priority, application Great Britain, July 22, 1965, 31,135/65; Mar. 18, 1966, 11,993/66 Int. Cl. D04!) 19/00 11 Claims ABSTRACT OF THE DISCLOSURE Yarn is crimped by forming it into a chain of stitches, setting the chain of stitches in the configuration of the stitches while the chain is under tension, and then unravelling the yarn from the chain. Apparatus for crimping includes a device for knitting yarn into a chain of stitches, positive driving means for conveying the chain under tension past a heater, and means for unravelling yarn from the chain of stitches.

This is a continuation of application Ser. No. 830,202, filed May 26, 1969, now abandoned, which application is a continuation of application Ser. No. 563,874, filed July 8, 1966, now abandoned.

This invention relates to crimping yarn, and more particularly to crimping thermoplastic yarn or yarn having a thermoplastic component.

It has already been proposed to crimp such yarn by knitting the yarn into a sheet or tube of fabric, placing the sheet or tube of fabric in a heated steam chamber to set the yarn in its knitted configuration and finally unravelling the crimped yarn from the sheet or tube of fabric after removal from the steam chamber.

I have noticed that yarn crimped in this manner cannot usually be produced having high internal crimp energy. I believe that this is because when the fabric is disposed in the steam chamber undergoing heat setting it is in a substantially relaxed form, so that the yarn takes up the loosest possible configuration having the maximum radius curves consistent with the number of stitches per inch in the knitted fabric, this being due to the resilient nature of the yarn and its consequent desire to return to a straight configuration. The crimped yarn when unravelled from the fabric does not include any sharp changes of direction along the yarn but only curved formations of a radius consistent with the number of stitches per inch in the kntited fabric.

Furthermore the production of crimped yarn in this manner tends to be inefficient.

It is an object of the present invention to provide a new method and apparatus for crimping yarn which is capable of overcoming or at least substantially reducing these disadvantages.

According to one aspect of the present invention there is provided a method of crimping yarn comprising forming the yarn into a continuous chain of stitches; passing the chain to a setting zone; heating the chain and simultaneously subjecting the chain to a controlled tension in the setting zone whereby the stitches are elongated and the yarn is set in this configuration; and then unravelling the yarn from the chain of stitches.

The yarn may be formed into stitches which, when the chain is subjected to tension and heat in the setting zone, incorporate sharp approximately 180 degree turns at each bend of the yarn therein, and the yarn intermediate the degree turns lies substantially parallel to the longitudinal direction of the chain.

Each stitch of the chain may comprise a loop in which the yarn passes through 360 degrees whereby the stitches when elongated are in the form of straight lengths of yarn, substantially parallel to the longitudinal direction of the chain, interconnected by sharp 180 degree turns.

I have found that by elongating the stitches in the chain by tension when the yarn is subjected to heat in the setting zone, it is possible to produce crimped yarn having high internal crimp energy.

I believe that the internal crimp energy of the crimped yarn produced is dependent on the degree of tension in the chain of stitches as the yarn passes through the setting zone coupled with the loss of resistance to bending and great decrease in resilience in the yarn when heated. By applying a tension in this zone the stitches are pulled out tight in the chain and so form sharp changes in direction within short lengths of yarn at the positions of interengagement of adjacent stitches. Since the yarn is then set with the stitches disposed in this elongated and distorted configuration the crimped yarn product will similarly tend to have sharp changes of direction, and these will have high crimp energy.

According to another aspect of the invention there is provided a method of crimping yarn including the steps of forming the yarn into an elongate series of stitches, passing the series of stitches through a heat setting zone under a controlled tension; and unravelling the yarn from the leading end of the series of stitches after it has passed from the setting zone whereby crimped yarn is produced.

According to yet another aspect of the present invention there is provided apparatus for crimping yarn including stitch forming means for forming the yarn into a continuous chain of stitches; tensioning means for applying a controlled longitudinal tension to the chain of stitches; heating means for heating the chain on the run while subjected to the longitudinal tension whereby the yarn is set in its distorted configuration; and unravelling means for unravelling the crimped yarn from the leading end of the chain of stitches after setting.

According to a further aspect of the present invention there is provided apparatus for crimping yarn including means for forming the yarn into an elongate series of stitches; means for applying a controlled longitudinal ten sion to said series of stitches; means for heat setting the stitch series while subjected to the tension; and means for unravelling the yarn from the leading end of the series of stitches after subjection to said means for heat setting.

I have found it particularly advantageous although not essential for the chain of stitches to have a width of only a single stitch. Alternatively, however, it is possible for the elongate chain to have a width of more than one stitch, for example up to about four or five stitches. Where the chain has a width of more than one stitch, the cross-section of the chain may include stitches linked together three dimensionally. Thus the chain may be constituted by stitches formed in a spiral sequence.

To produce a uniformly crimped yarn, the longitudinal tension to which the chain is subjected in the setting zone should be maintained uniform. I have realised that variations in tension across the width of the chain have the efiect of creating variations in the crimp of the treated yarn. As the width of the chain increases so the difiiculty of maintaining the longitudinal tension uniform across the width of the chain increases.

It is to be appreciated that to produce completely uniformly crimped yarn by means of the invention it is necessary for the configuration of each stitch formed to be exactly the same as the configuration of every other stitch.

In some cases, of course, it may be desired to produce a yarn which is not completely uniformly crimped, but to produce yarn instead having a crimp which varies regularly or intermittently along its length. In this case a stitch formation which causes a varied stitch configuration can be used in the present invention.

It has been found simple and effective to provide said chain of stitches as a chain of crocheted stitches of single stitch width.

It is possible to form said chain of stitches from a single end of yarn or from two or more ends formed together into the chain and subsequently separated into separate yarns. The two or more yarns may lie formed into said chain either as a combined yarn or as individual yarns. The two or more yarns can each be drawn from a separate supply package. The two or more crimped yarns may be separated from each other during the unravelling and each crimped yarn may be wound on to a separate take-up package.

In one embodiment of the invention the yarn is positively fed into the setting zone and positively fed from the setting zone whereby the tension in the setting zone is controllable by controlling the rate of positive feed into and/or from the setting zone.

Thus the controlled tension in the setting zone may be provided by means of a set of positive drive means such as yarn feed rollers disposed before the setting zone and a second set of positive drive means such as yarn feed rollers disposed after the setting zone.-By adjusting the relative yarn driving speeds of these two sets of rollers, hereinafter referred to as tensioning feed rollers, it is possible to subject the yarn in passage through the setting zone to the required amount of tension for the particular quality crimped yarn to he produced.

The setting zone may incorporate any suitable form of setting means known in the art, and the setting means may for example comprise an electrically or hot oil heated heating plate or element having a contact face over which the chain of stitches is arranged to pass so as to be heated by contact therewith, and the yarn softened thereby; the contact face may be convex along the direction of yarn path. In this case the chain is arranged to cool below the softening temperature thereof before passing through the second set of tensioner feed rollers so that the yarn is set in its distorted configuration at a controlled tension.

I have found that the permanence of the crimp set in the yarn is related in some yarns, such as nylon 66, to the amount the yarn is allowed to shrink when subjected to heating in the setting zone. In this case if the chain is subjected to a tension of suflicient magnitude substantially to prevent the yarn shrinking during heat-setting, the crimping produced may tend to be of a mild nature and the yarn only lightly bulked. To produce bulky yarn of high internal crimp energy I have found with these yarns that where the setting zone tension is provided by means of the sets of tensioning feed rollers a suitable amount of tension in the setting zone may be provided by in fact overfeeding the chain of stitches into the setting zone by a predetermined amount to allow the yarn to shrink but such that the shrinkage of the yarn during heating in the setting zone produces sufficient tension in the chain to pull the then softened stitches out tight in the manner necessary to produce crimped yarn of high internal crimp energy.

Again with some other yarns, such as polyester yarn I have found that an approximately zero overfeed into the setting zone results in the production of crimped yarn of high internal crimp energy.

The crimped yarn is unravelled from the chain of stitches after heat setting. This may be done by pulling the crimped yarn from the leading end of the chain under tension. In one embodiment of the invention the chain is passed in succession through two positive drive means such as two unravelling sets of positive feed rollers, the later set of which is arranged to be driven faster than the earlier set, the yarn being unravelled from the chain between the tWo unravelling sets of rollers. The speed of drive of the two sets of rollers is desirably so correlated so as to maintain the point of unravelling more or less stationary, e.g. at a position near the earlier set of rollers. In other words the ratio of drive speeds of the two sets of unravelling rollers are desirably arranged to be such that the increase in yarn length caused by the unravelling is exactly related to the greater speed of the second set of rollers.

Should the point of unravelling of the chain accidentally pass from between the two unravelling sets of feed rollers, i.e. move forward to the second unravelling set of rollers if the second set is driven relatively too slowly, or move back to the first unravelling set of rollers if the second set is driven relatively too fast, the tension in the yarn between the unravelling sets of rollers will greatly increase due to the differences of speeds of the sets of rollers.

This increase in the tension could quite possibly lead to a breakage in yarn. To prevent this there may be provided means engaging the yarn between said unravelling sets of rollers and adapted to cut out or adjust the speed of the motor or motors driving the first and second set of unravelling rollers when the tension in the yarn exceeds a predetermined limit. Conveniently said means may also be arranged to cut out said motor or motors in the event of the yarn between the unravelling sets of rollers being broken.

The first unravelling set of rollers may be constituted by the second set of tensioning feed rollers. In this case the ratios of the driving speeds of the three sets of rollers, together with the speed of a crimped yarn take-up mechanism, the speed of a stitch forming mechanism and the temperature of the yarn setting zone are all interrelated variable factors aflecting the crimped yarn produced and their values can be selected bearing in mind their interrelationship to produce yarn of a particular bulkiness, crimp rigidity, crimp frequency and crimp retentivity on: a package of particular density.

The apparatus preferably includes winding means for winding the unravelled yarn into a package.

The yarn may be formed into said chain of stitches by any practical knitting arrangement. Thus part of a standard known form of knitting machine may be used to produce the chain of stitches. In one embodiment of the invention however the series of stitches is formed by means of a single needle oscillating relative to and adjacent a yarn guide which is arranged to guide yarn into knitting engagement with the needle. The needle may be of any known form capable of forming the desired stitch and may advantageously comprise a latch or a bearded needle or a hook member. When a latch or bearded needle is' used it may be necessary to provide means to close the latch or beard respectively during an appropriate part of the stitch forming cycle.

I have found a bearded needle to be useful and convenient in forming said series of stitches accurately and efficiently.

According to yet another aspect of the present invention crimped yarn is constituted in the relaxed state by a series of sharply angled uniform V-like shapes each having one side longer than the other, and having the general plane of each V-like shape disposed at an acute angle to a medial plane running in the general lengthwise direction of the yarn, the longer side of each V- like shape having a slight bend approximately midway along its length.

The longer side of each V-like shape may be approximately twice the length of the shorter side.

In order that the invention may be more readily understood embodiments thereof will now be described by way of example with reference to the accompanying di agrammatic drawings in which:

FIG. 1 is a general perspective view of a yarn crimping apparatus according to the invention;

FIG. 2 is a perspective view, partly broken away, of the knitting station of the apparatus of FIG. 1;

FIGS. 3a, 3b, 3c and 3d illustrate the stitch knitting cycle of the knitting station of FIG. 2;

FIGS. 4a, 4b and 4c illustrate the preparation of a chain of stitches before commencing unravelling the chain;

FIG. 5 shows a chain of stitches under some tension;

FIG. 6 shows the chain of stitches of FIG. 5 after the stitches have been tightened;

FIG. 7 shows a side view of crimped yarn;

FIG. 8 shows a top view of the crimped yarn of FIG. 7;

FIGS. 9a, 9b and 9c show a driving motor cut out of the apparatus of FIG. 1 in three different operating positions;

FIGS. 9d, 9e and 9f are cross-sections on the lines da', ee and ff on FIGS. 9a, 9b and 9c respectively; and

FIG. 10 is a schematic plan view of an apparatus according to the invention for the simultaneous crimping of two yarns.

Referring now particularly to FIG. 1 of the drawings, it will be seen that there is illustrated a crimping unit capable of crimping a single yarn in accordance with the invention. The basic features of the apparatus are, reading progressively along the yarn path indicated by the chain dotted line, a yarn supply bobbin 1, a knitting station 2, positive feed nip rollers 6 and 7, positive feed rollers 8 and 9, and a crimped yarn take-up bobbin 10.

Having described the basic principles of this embodiment of the invention the apparatus illustrated will now be described in greater detail.

The whole crimped unit is mounted on a fixed framework most of which is omitted from the drawings for simplicity. This framework is of an iron or steel construction and is arranged to carry a plurality of units of the kind shown in FIG. 1 disposed side by side and back to back. By this means, for example 100 units can be disposed on a single elongated framework.

The bobbin 1 is arranged to be carried by a support member of any well known kind disposed at the base of the framework and not shown for the sake of simplicity. The support member may comprise part of a creel arrangement by means of which two bobbins of supply yarn may be placed adjacent each other so that the tail end of the yarn of a bobbin currently supplying yarn to the crimping unit can be knotted to the leading end of yarn on a full bobbin whereby supply of yarn to the unit can be arranged to be continuous.

The supply yarn passes from the bobbin 1 between the spring urged blades of a tensioner 14 via guides 15 and 16. The tensioner 14 has the effect of tensioning the yarn sufliciently for it to be manageable at the knitting station 2.

The knitting station 2 comprises (as shown most clearly in FIG. 2) a bearded needle 17 fixedly secured to an arm 18 forming part of a metal block 19 which in turn is fixedly mounted on the machine framework (not shown). Journalled through the block 19 is a shaft 20 which carries on the side remote from the needle 17, a pulley 21 rotatable with the shaft 20. The shaft 20 is driven by an electric motor 22 mounted on the machine framework (not shown), via a belt 23 passing around a pulley mounted on the spindle of the motor 22, and around the pulley 21.

A crank wheel 24 is mounted on the shaft 20 on the side of the block 19 adjacent the needle 17. Pivotally and eccentrically mounted on the wheel 24 by means of a pin 25 is a reciprocating rod 26. The rod 25 is journalled through a bearing block 27 which is secured to the block 19 but is capable of rotation thereupon about an axis perpendicular to the block 19.

Attached to the end of the reciprocating rod is a yarn guide assembly .28 which comprises arms 29 and 30 on each side of the needle 17 having eyes 31 and 32 respectively through which the yarn is arranged to pass, and a sapphire stud 33 so disposed as to close the beard of needle 17 during the appropriate part of the knitting cycle.

After the yarn is knitted into the chain of stitches 12 (in a manner to be described in detail hereinafter), the chain is passed through a ceramic guide 34, mounted by means of a support 35 on the framework (not shown), to the rubber surfaced roller 3. The roller 3 is rotatably carried by a plate 36 which in turn is pivotally mounted on an axle 3-7. The roller 3 is urged into contact with the steel roller 4 by means of a spring 38 acting on the plate 36. The axle 37 is mounted, via a mounted block 3-9, on a smooth steel rod 40 forming a longitudinally extending portion of the machine framework (not shown).

' The roller 4 is mounted on an axle 41 which carries a driving pulley 44 and is driven by the motor 22 via a belt 45, a pulley 46, a pulley 47 and belt 48.

The rollers 3 and 4 constitute a first set of tensioning feed rollers and the yarn chain 12 is wound a number of times (e.g. three times) around the rubber covered roller 3 and an adjacent ceramic yarn separating guide 49 so that the rollers 3 and 4 nip the yarn chain between them and positively feed it through guide 34 over a guide 50 and into engagement with a heater 5 constituting part of a yarn setting Zone.

The heater 5 is an electrically heated device provided with a case 51 packed with insulating material surrounding on three sides an elongated heating element 52. The element 52, is heated in a known manner by electric resistance wires (not shown) disposed closely adjacent the rear surface thereof. The temperature of the element 52 is thermostatically controlled in a known manner, and an adjusting switch 53, disposed adjacent an indicating light 54, is provided for adjusting the temperature of the element to provide appropriate heating for the particular yarn to be crimped. The element 52 is provided with two grooves 55 and 56 along its length, so that the chain of stitches 12 passes down groove 56 in contact with element 52, around a guide 57 mounted below the heater 5 on the framework and then up the groove 55 in contact with element 52 before passing over the guide 50 and away from the heater. The face of the element 52 containing the grooves 55 and 56 is slightly convex along its length whereby the chain 12 is held in close contact with the element 52 during its travel along the heater.

After the heater 5 the chain of stitches passes through the atmosphere for a sufiicient distance to cool and then over a smooth steel rod 40 to the rubber surface roller 6 which is urged by spring means (not shown) against the steel roller 7. The roller 7 is mounted on a shaft 58 rotatably mounted in brackets 60 forming part of the framework, which carries a driving pulley 59 and which is driven by the motor 22 via a belt 61, pulley 72, pulley 47 and belt 48.

The rollers 6 and 7 constitute a second set of tensioning feed rollers, and the chain 12 is wound a number of times (e.g. three times) around the rubber covered roller 6 and an adjacent yarn separating guide 62, so thatthe rollers 6 and 7 nip the yarn chain between them and positively feed it away.

After passing through the feed rollers 6 and 7 the stitch chain engages a motor cut out device 63, the operation of which will be described in detail hereinafter, the yarn then passing around a ceramic guide 64 and between the nip of the rubber surface roller 8 and the steel roller 9 urged together by a spring (not shown).

It is to be observed that the feed roller 7 has a conical outer surface. This is to provide accurate infinitely variable adjustment over a predetermined range of the peripheral speed of the roller 6, and thus of the speed of positive drive imparted to the yarn chain. The peripheral speed of the roller 6 is adjusted by moving it axially relative to the conical roller 7.

The operation of the crimping apparatus is arranged. such that the yarn chain 12 is unravelled between the: rollers 6 and 7 and the rollers 8 and 9, and the crimped: yarn 13 is then fed by the rollers 8 and 9 towards the: take-up package 10. It will be seen that the roller 9 ismounted on an axle 41 so that the rollers 8 and 9 are driven, as are the rollers 3 and 4, by the motor 22 via. pulley 44, belt 45, pulley 46, pulley 47' and belt 48.

From the rollers 8 and 9 the crimped yarn 13 is fed. through a ceramic guide 65 to a yarn traverse guide 66 carried by a reciprocatory wire 67 forming part of a machine traverse mechanism which is not shown but which. conveniently may be of the kind disclosed and illustrated. in US. Pat. No. 3,018,974. The crimped yarn is then wound on to take-up bobbin 10. This bobbin is mounted on a spindle 67 which can rotate within, as well as being slidable along, grooves 68 extending vertically in support arms 69. The arms 69 are rigidly secured to a steel bar' 70 which forms part of and extends along the framework of the multiple unit machine.

The spindle 67 slides, under the action of gravity, down the grooves 68 until the outer surface of bobbin 10, or the outer surface of a yarn package being wound upon it, engages with the surface of a cork covered drum 71. The drum 71 is mounted alongside roller 7 on the shaft 58- and is therefore driven in a like manner from the motor 22 by means of pulley 59, belt 61, pulley 72, pulley 47 and belt 48. Hence the take-up bobbin is driven by surface contact with drum 71 so that constant speed take-up of the crimped yarn as the package grows is ensured. By mounting the bobbin spindle 67 within the grooves 68,. easy removal of full packages from the unit is ensured, and relative separation between the drum 71 and bobbin. 10 to accommodate the growth of the package is simply accomplished.

Operation of the stitch forming station will now be described in detail with reference to FIGS. 3a, 3b, 3c and 3d.

The actual shape and configuration of the chain of stitches is clearly shown in FIGS. 4a, 4b, 4c, and 6, which will be described in detail hereinafter.

FIGS. 3a, 3b, 3c and 3d represent the needle 17 and yarn guide 28 at four different operational positions during the knitting cycle of the stitch forming station 2. The arrows 72 with each figure represent the position in each figure of the yarn guide 28 with respect to its oval shaped path of movement, the total path being shown most clearly in FIG. 3d. This oval path is caused by the circular motion of the crank wheel combined "with the movement of the rod 26 in the pivot bearing 27.

In FIG. 3a the loop 73 of a stitch being formed is disposed at the rear end 74 of the needle 17. The chain of already formed stitches 12 extends through the eye 31 in the arm 29, and the uncrimped yarn to be knitted extends through the eye 32 in the arm 30.

In the position shown in FIG. 3a, the guide 28 has begun to move forward and upward from its most rearward position. The loop 73 is being moved forward along the fixed needle toward the open beard 76 and a length of yarn 75 for the next stitch passes partly around and in contact with the needle.

In the position shown in FIG. 3b the guide 28 has moved forward approximately half of its full forward movement and is at about its highest point. The length of yarn 75 has moved into the beard 76 of the needle 17, and the sapphire stud 33 has closed the beard after it, so that the loop 73 is prevented from entering the beard and moves along outside it.

In FIG. 30 the guide 28 is in a position after it has the newest stitch in the chain 12. The length of yarn 75 has been caught in part between the needle 17 and the loop 73 to form a new loop 77. The sapphire stud has disengaged from the beard 76 which is again open.

In FIG. 3d the guide 28 is approximately half way along its rearward travel and at approximately the fullest extent of its downward travel. The new loop 77 on the needle 17 is moving backwardly along the needle out of the beard 76. The sapphire stud 33 is now below the level of the beard 76 and does not therefore engage and close it. The knitting cycle is almost in position to recommence.

The configuration of the crochet stitches in the chain 12 and the way in which they are caused to unravel will now be described with reference to FIGS. 4a to 40. For simplicity, a short length of chain 12 of loosely formed crochet stitches is shown. As can be seen, each stitch is formed with a loop of yarn extending through approximately 360 degrees. This can more readily be appreciated by following the yarn in the first stitch 101 from the free end 102 of the yarn, back through the 360 degree loop 103, until at 104 the yarn passes to the next stitch. If the free end 102 were pulled, then the loop 103 would wind tightly around the yarn of the next stitch and form a knot so preventing the chain 12 of stitches unravelling. However, if the first part of the loop 103 is engaged by a hand hook 105 as shown in FIG. 4a, and then pulled downwards through the loop 103 as shown in FIG. 4b, the free end 102 will pass downwards from the loop 103 as shown in 'FIG. 40. From the posi tion in FIG. 40, if the free end 102 is pulled, the stitches will now unravel one after the other and no knotting will occur. This technique is used when starting-up the crimping process.

FIG. 5 illustrates the form of the chain of stitches 12 when subjected to a controlled tension before passing over the heater 5. As the chain 12 passes over the heater 5 the stitches are pulled tight and take on a configuration as illustrated in FIG. 6; in this configuration the stitches are elongated and constricted in width so that the chain tends to be formed by long and short lengths of yarn connected together by sharp degree bends, the radius of curvature of the inside of each such bend being approximately the diameter of the yarn. It is believed that the tightening of the stitches is partly due to the tension in the chain and the yarn becoming more pliable due to the heat.

It has been found that crimped yarn can be produced in the above way having a substantially uniform crimp, the crimped yarn being formed by a series of uniform Waves of V-like shape. By adjusting the size of stitch formed, the tension in the chain of stitches during heating, and the degree of heating, the size and configuration of the VS can be determined. Thus a crimped yarn having large V's or a crimped yarn having small Vs can be obtained. An example of the crimped yarn is shown in side view in FIG. 7; each wave 106 can be seen to be formed by a V-like shape in which one side 107 is approximately twice the length of the other side 108. Also, the longer side 107 has a slight bend 109 about midway along its length. Each V-like shape is slightly off-set to the general plane of the crimped yarn as can be seen from FIG. 8 which is a top view taken approximately in the direction of the arrow A in FIG. 7. It will be appreciated that the crimped yarn shown in FIGS. 7 and 8 has a three dimensional crimp; if the Vs 106 in FIG. 7 are viewed as saw teeth, then as seen in FIG. 8 the saw teeth have a set similar to real saw teeth. For simplicity, a crimped monofilament yarn has been shown in FIGS. 7 and 8.

FIGS. 9a to 9 illustrate the operation of the motor cut out device 63.

As seen in FIG. 1 this device is disposed in the yarn path between guide 62 and guide 64, i.e. in the part of the yarn path where the chain 12 is unravelled into crimped yarn 13, and the device is intended to stop motor 22 should the yarn break, or should the tension in the yarn exceed a predetermined limit, due for example to the point of unravel moving into the nip of rollers 6 and 7 or 8 and 9 (as mentioned generally above), or due to a snag or similar yarn defect preventing unravelling.

The device 63 includes three electrical contact spring blades 78, 79 and 80 carrying contact studs 81, 82 and 83, 84 respectively. The contact blades 78 and 80 are connected via leads (not shown for simplicity) to a starter device (not shown for simplicity) of a known type having a solenoid actuated cut out and reset mechanism.

The spring contact blades are screwed to an insulating block 85 which is attached by means of a bracket '86 to the machine framework. A wire hook 87 is secured to the end of the contact blade 78 and yarn 88 passing from guide 62 to guide 64 is arranged as shown in FIGS. 9a and 9c to be deflected so as to run through the hook 87. A stop motion 89 is provided to limit the upwards movement of hook 87.

The normal operating position of the device 63 is illustrated in FIGS. 9a and 9d with the yarn under normal operating tension. The blades 79 and 80 are naturally spring urged together to make contact between studs 83 and 84, and the tension in the yarn is suflicient to hold the blade 78 against the blade 79 against the tendency of the blade 78 to move downwards from blade 79. Hence studs 81 and 82 make contact. It will be seen therefore that blade 79 acts as a contact bridge to blades 78 and 80, and so maintains closed a circuit incorporating the above mentioned solenoid reset of the starter unit.

In FIGS. 9b and 9e the device is shown in the position it adopts in the absence of yarn engaging in the hook 87, because of yarn breakage for example. It will be seen that although blades 79 and 80 are still pressed together, blade 78 is no longer pressed upwards against blade 79 by yarn in the hook 87 and therefore by its natural resilience moves out of contact with blade 79. Hence the circuit through blades 78 and 80 and including the solenoid reset of the starter unit is broken and the motor 22 (FIG. 1) is switched Ofi.

FIGS. 90 and 9; illustrate the position of the device 63 when the tension in the yarn 88 becomes excessive, for example because of the inability of the yarn 88 to unravel for some reason. The tension in the yarn 88 acts as if to remove the deflection in its path of travel, so that the blade 78 is pulled up by the yarn to the extent that it moves blade 79 upwardly and separates it from blade 80, so that again the solenoid reset circuit is broken and the motor 22 switched off.

In FIG. 10 is schematically illustrated the aforementioned embodiment in which a plurality of yarn ends is formed together into the chain and subsequently separated into separate yarns. Supply yarns 11 and 11 are led from respective bobbins 1' and I through the tensioner 14' to the knitting station 2' where they are formed into the chain 12'. The rollers 3' and 4, through the nip of which the chain is passed, tensions the chain in the manner heretofore described. The chain 12 is then heated by the heater 5, withdrawn therefrom by the rollers 6' and 7, and unravelled between the rollers 6' and 7 and the rollers 8 and 9' as heretofore described. The resultant crimped yarns 13 and .13 are wound on respective take up bobbins and 10".

It is to be appreciated that in the operation of the crimping unit particularly described, the peripheral speeds of the two sets of tensioning feed rollers, the knitting speed, the needle shape and movement cycle characteristics, and the temperature of the heater are all interrelated factors controlling the crimp of the yarn, and are arranged and adjusted in relation to each other to produce a crimped yarn with particular crimp properties. Control of these variables is possible with great accuracy, leading to accurately and uniformly crimped yarn.

I have found that when crimping nylon yarn for example a resultant yarn of desirably high crimp energy can be produced if the peripheral speeds of the two sets of tensioning feed rollers are adjusted to overfeed the chain over the heater so as to permit shrinkage of the yarn during heating, for example of the order of 1% to 2%. The natural shrinkage of the nylon yarn is sufi'lcient to provide the tension required to elongate the stitches in the chain and hence produce the desired high crimp energy in the resultant crimped yarn.

On the other hand I have found that when crimping polyester yarn for example, a high crimp energy yarn can be produced with zero overfeed to the heater.

The peripheral speed of the rollers may be adjusted by varying the rate of rotation of the rollers or alternatively by utilising rollers of different radii for different speeds.

Again to ensure correct unravelling of the yarn the relative speeds of the unravelling sets of rollers 6 and 7, and 8 and 9 are accurately interrelated so as to allow for the increased yarn length between them. Such interrelation is easily made possible by means of the adjustability of the peripheral speed of the roller 6 as mentioned hereinabove. By adjusting the peripheral speed of roller 6 the relative drive speeds of the unravelling sets of rollers can be finely adjusted to reduce or even prevent movement of the unravelling point.

In some case, particularly when crimping multifilament yarn, means may be provided to increase the three dimensional bulkiness of the crimped yarn produced. Such means may comprise a sharp edge device or an air blast device of known type arranged to engage or act upon the yarn after it has been unravelled from the chain and before it is wound on to the bobbin 10 and separate the filaments of the yarn to a certain extent.

It is to be observed that with the apparatus described the tension for winding the yarn package on bobbin 10 is independent of the tension required for unravelling the yarn from the chain 12. Thus by appropriately correlating the rate of rotation of the drum 71 and the speed of reciprocation of the traverse guide 66 with the rate of rotation of the feed rollers 8 and 9 it is possible to provide a package of high or low density as may be required for the subsequent use of the yarn.

Examples of crimped yarn produced in the above way will now be given:

EXAMPLE 1 15 denier monofilament nylon 66 was processed as particularly described above. The chain was formed with 24 stitches per inch at a rate of 5,000 stitches per minute. The heater 5 was set at 210 C. and each groove of the heater was 30 inches long. The chain passed to the heater at a rate of 200 inches per minute. The two sets of tensioning feed rollers were so arranged that the yarn was overfed to the heater to allow 1% shrinkage of the yarn during heating. The crimped unravelled yarn was fed by rollers 8 and 9 at a rate of 594 inches per minute and overfed by approximately 4% on to take-up bobbin 10.

EXAMPLE 2 With 400 denier 50 filament nylon 66, the chain was formed with 8 stitches per inch at a rate of 5,000 stitches per minute. The heater 5 was set at 220 C. The chain passed to the heater at a rate of 625 inches per minute, and the overfeed to the heater was arranged to allow 2% shrinkage of the yarn during heating. The crimped unravelled yarn was fed by rollers 8 and 9 at a rate of 1,838 inches per minute and overfed by approximately 4% onto take-up bobbin 10.

EXAMPLE 3 With denier 30 filament polyester, the chain was formed with 15 stitches per inch at a rate of 5,000 stitches per minute. The heater 5 Was set at C. The chain passed to the heater at a rate of 333 inches per minute,

1 1 and in this case there was no overfeed to the heater and only slight shrinkage of the yarn during heating was possible. The crimped unravelled yarn was fed by rollers 8 and 9 at a rate of 1,000 inches .per minute and overfed by approximately 4% onto the takeup bobbin 10.

By the present invention crimped yarns having a wide range of stretch properties, bulkiness, and crimp rigidity can be produced. Throughout this wide range the crimped yarns can be produced with a precision and uniformity in crimp formation that has hitherto been difficult to obtain commercially, and could not before he obtained over a wide range.

The precision and uniformity in crimp is believed to be due to the accuracy and controllability of the apparatus and method of the invention; thus great control can be achieved over the size of the stitches in the chain together with the temperature to which the stitches are heated. The accuracy and controllability of the process and apparatus lead to a great technical advantage over prior crimping techniques.

Also, by the present invention it is possible to lock a large amount of energy in the crimped yarn, that is in the bends, due to the sharp 180 degree bends being intimately heated, while in this configuration; by the present invention it is possible to lock more energy in the crimped yarn than has been possible by, for example, the stuffer box crimping process.

The range control over the size of the crimp is achieved by varying the number of stitches per unit length and also by changing the size of the needle. In this way, the number of stitches per unit length is infinitely and controllably variable from, for example, 4 to 40 stitches per inch. 1

The dye aifinity of the crimped yarn has been found to be even, particularly with polyester yarn, and this is believed to be due to the uniform thermal treatment of all the yarn while in its highly distorted configuration.

It has also been found that yarn produced, for example, by the particular embodiment of the invention described and illustrated hereinabove is particularly advantageous compared to yarn produced according to the method mentioned earlier in which the yarn is crimped by knitting the yearn into a sheet or tube of fabric, placing the sheet or tube of fabric in a heated steam chamber to set the yarn in its knitted configuration and finally unravelling the crimped yarn from the sheet or tube of fabric after removal from the steam chamber.

When yarn is crimped in the manner of the said method mentioned earlier, the resultant crimps in the yarn may be of the same general configuration as the stitches into which the crimped yarn is knitted when the ultimate articles are produced from the yarn. Because of this, great care has to be taken in selecting the size and configuration of the stitches in the setting fabric and the ultimately produced article to prevent the stitches of the ultimate article periodically forming in phase with the crimp configuration. Such phasing results in a non-- homogenous article of unsatisfactory quality.

On the other hand, yarn produced by the apparatus and method particularly described above, is of a totally different configuration from the stitches of articles into which it will be knitted so that the problem of phasing is avoided.

What is claimed is:

1. A method of crimping yarn, comprising continuously and on the run carrying out the following squence of steps:

(a) forming the yarn into a chain of stitches each of which comprises a loop passing through the loops of adjacent stitches,

(b) positively feeding said chain to a setting zone at a first rate,

(c) passing the chain through the setting zone,

(d) positively withdrawing said chain from the setting zone at a second rate, said second rate being greater than the first rate whereby the yarn of each loop is bent sharply around the yarn of adjacent stitch loops and the yarn is set in this configuration, and

(e) downstream from said positive withdrawing at said second rate positively driving said yarn at a third rate, said third rate being sufficiently greater than said second rate to cause unravelling'of the thusly crimped yarn from the leading end of said chain between the point of said withdrawing at said second rate and the point of said driving at said third rate.

2. A method of crimping yarn according to claim 1, in which the chain of stitches formed is of single stitch width.

3. A method according to claim 1, in which said stitches are crochet stitches.

4. A method according to claim 1, in which said setting zone comprises a heating zone.

5. A method according to claim 1, in which said chain is formed of a plurality of yarns and said yarns are separated after said chain is unravelled.

6. A method according to claim 1, in which said chain is formed from a multi-ply yarn and the yarns constituting said multi-ply yarn are separated after said chain is unravelled.

7. A method according to claim 1 further comprising pre-tensioning the yarn prior to forming it into said chain whereby the yarn is tensioned as it is formed into said chain.

8. A method according to claim 1 further comprising winding the crimped yarn.

9. A method of crimping yarn, comprising continuously and on the run carrying out the following sequence of steps:

(a) forming the yarn into a chain of stitches each of which comprises a segment of yarn passing around the segment of yarn of another stitch,

(b) feeding said chain to a setting zone at a first rate,

(c) passing the chain through the setting zone,

(d) positively withdrawing said chain from the setting zone at a second rate, said second rate being so related to the first rate that the segments of yarn passing around other segments of yarn are bent sharply around the other segments of yarn and the yarn is set in this configuration, and

(e) downstream from said positive withdrawing at said second rate positively driving said yarn at a third rate, said third rate being sufliciently greater than said second rate to cause unravelling of the thusly crimped yarn from the leading end of said chain between the point of said withdrawing at said second rate and the point of said driving at said third rate.

10. A method according to claim 9, in which each of the stitches of the chain formed in step (a) comprises a segment of yarn passing around the segment of yarn of another stitch and in step (d) each of the segments of yarn passing around other segments of yarn are bent sharply around the other segments of yarn and the yarn is set in this configuration.

11. A method according to claim 10, in which the second rate is greater than the first rate.

References Cited UNITED STATES PATENTS 6/1952 Page 2872.l6(X) 8/1967 .Soussloif et al. 2872.16(X) FOREIGN PATENTS ROBERT R. MACKEY, Primary Examiner US. Cl. X.R. 

